Meteor hunting and how to differentiate between a space rock and a terrestrial rock



If you look at the sky at night long enough, you will almost certainly see a shooting star – a bright, fine light that pierces the sky.

Shooting stars, or meteorites, are often the last we will see of the rock that caused its bright flash in the sky when it burns in our atmosphere.

Most of the time, the object that caused the shooting star is no bigger than a grain of sand, and not much will hit Earth.

But sometimes they are bigger and they break into pieces and land on Earth.

The Desert Fireball team at Curtin University has installed cameras across Australia to monitor large meteorites, fireballs, that could leave behind meteorites, to try to locate them quickly.

They know that not many meteorites have been found, and they are out there, waiting for their discovery.

Two women outside who seem windswept hold a small piece of rock.
Astrophysicist Tamara Davis and astrogeologist Gretchen Benedix with a meteorite.(ABC catalyst.)

Gretchen Benedix, an astrogeologist on the Desert Fireball team, says finding a piece of space rock is exciting every time.

“You do some happy dancing. But it’s absolutely 100 percent exciting about the moon every time because it’s a rock from space,” says Professor Benedix.

So what are the chances that you can pick up a piece of space rock?

Although meteorites are very rare, they are out there, and it is not impossible that you can find one, especially if you know what you are looking for.

Meteors, meteorites, meteorites?

Names can be a bit confusing: what is an asteroid? A meteor? A meteoroid?

The best way to ensure that you are using the correct name is to think about size and location.

Essentially, asteroids and meteoroids are very ancient space rocks, orbiting in our solar system, primarily in the asteroid belt between Mars and Jupiter.

All planets, including Earth, are the product of those rocks that collided and formed together 4.6 billion years ago.

Some pieces were too small and too far apart to form planets and remained in space, orbiting the asteroid belt.

Asteroids They are the largest rocks, ranging from a couple of meters in diameter to almost a kilometer in size and meteoroids they are much smaller, generally less than a meter, and can be much, much smaller.

Occasionally, asteroids and meteoroids are disturbed, by colliding with other rocks, and are sent out of the asteroid belt and sometimes towards Earth.

A meteoroid or an asteroid is called meteorite when it travels through our atmosphere, glowing brightly. Once it lands, the pieces that hit the ground are called meteorites.

Large asteroids have hit Earth, like the 12km-wide asteroid that likely killed the dinosaurs, but it’s not likely to happen again soon.

The shooting stars you can see at night are probably meteorites, but they are probably too small to leave a meteorite.

The larger meteorites, which look like much brighter and brighter shooting stars or fireballs, are more likely to survive part of the entrance, breaking into pieces that scatter and land on the ground like meteorites.

“There are about 60,000 meteorites on Earth’s surface that we have now cataloged. They are still extremely rare materials in the solar system,” says Professor Benedix.

Where is the best place to look for a meteorite?

A large dark colored mottled rock on a black background.
Part of what makes the Murchison meteorite so special is how long it survived entry into Earth’s atmosphere.(Supplied: Rodney Start (Victoria Museums))

No place is more likely than any other that a meteorite will break and leave meteorites there, but it is much easier to find a meteorite in some places than in others.

Some land in the ocean, or in other places that are difficult to access or search, such as thick rain forests.

There is a place where scientists who study space rocks love to hunt: Antarctica.

That’s because if they find a black rock in Antarctica, they can guarantee that it is a meteorite. And a black rock between a large amount of white ice is very easy to detect.

But while Antarctic space rock hunting trips are a bit difficult to organize, there are some places that are better for hunting for meteorites.

It will be easier to find a meteorite on the ground if the surface is smooth, flat and not covered in black rocks.

It’s definitely worth investigating your own backyard or local park, even better if that area is empty or empty. While meteorites are rare, they are out there!

Is the rock you found a meteorite? Follow this flowchart to find out.(Supplied: Fireballs in the sky)

What to look for: meteorites and meteorites

  • Black Bark: Meteorites can be made of different materials, but they all have one thing in common: they must all have fallen through Earth’s atmosphere and landed on the ground. That trip through the atmosphere of up to 60 km per second will cause the exterior of the rock to melt, forming a thin, shiny black exterior, called the fusion crust. In rocks that have been in the ground for a while, the melting crust may have come off, revealing that the rock has a different color inside. That is a useful sign.
  • Heavy: A meteorite is a dense rock, sometimes with iron inside it, so it should feel heavier than a normal terrestrial rock of the same size.
  • Soft dents: Looking at the rock surface, you may be able to see smooth indentations, which appear to have pressed your thumb against the rock and left an impression, like soft clay. Those are called regmaglypts. It should have smooth or rounded edges, rather than sharp rocky points.
  • Magnetic: Use a magnet to see if the rock is magnetic. About 90 percent of meteorites are magnetic. If the rock clings to its magnet, even weakly, that could be a sign that it is a meteorite. But it is not a guarantee, because terrestrial rocks can be magnetic, like iron-rich terrestrial rocks or magnetite. The industrial by-product can also be magnetic and look like a meteorite.

If you think your rock is a meteorite, or even a meteorite, maybe send a photo to the Desert Fireball Network team for a meteor expert to take a look.

Either way, send us a photo of your findings via the ABC Science Facebook page.

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